Process of producing from ligno-cellulose fermentable sugar.



M. F. EWEN & G. H. TO MLINSON. rnoonss'or PRODUCING PROM LIGNO-GELLULOSB FERMENTABLE SUGAR. APPLICATION FILED JULY 26,1909.

938 ,308, Patented Oct. 26, 1909.

I MALCOLM F. EWEN AND. GEORGE H.

unrrno STATES PATENT OFFICE.

TOMLINlSON, OF CHICAGO, ILLINOIS.

PROCESS OF PRODUCING FROM IIIGNO-CELLULOSE FERMENTABLE SUGAR.

Specification of Letters Patent. v Patented Oct, 26, 1909,

Application filed-July 26, 1909. Serial No. 509,680.

To all whom it may concern:

Be it known that we, MALCOLM F. EWEN and Gnonen H.. TOMLINSON, citizens of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improve I ment in the. Process of Producing from Ligno-Cellulose Fermentable Sugar, of which the following is a specification.

This invention relates to a process of treating large quantities of ligno-cellulose for the purpose of producing fermentable sugar in large quantities which is adapted to be easily quickly and efliciently converted into alcohol.

The accompanying drawing shows a diagrammatic view illustrating a form of apparatus for carrying out the process.

In the drawing. is illustrated two closed vessels or digesters 1 and 2. The digesters may be of various forms, and the forms illustrated are approximately s herical in sha e; These digester-s are pre'f drably revolul fly mounted upon a suitable support. As herein shown the digesters are revolubly mounted about the pipes 3 and 4, by means of which steam is introduced therein. Each of these pipes is connected to a suitable source of steam supply. These pipes are provided with a series of openings, prefer ably located on the lower side thereof, so as to distribute the steam over a large area. Each digester is provided with an opening which, as'shown, consists of a man-hole 5, by 'means of which material ma be inserted and removed. In ordert-o faci itate the introduction of the acid and the ligno-cellulose there is provided above the dig-esters the hoppers 6 into which the proper quantity of ligno-cellulose may be lnserted, and this ligno-cellulose may be easily and quickly discharged into the digesters when desired. There is also associated with each digester an acid tank 7, which is preferably ameasuring tank so that a proper quantity of acid may be introduced. The and is preferably 1nan-hole is closed and steam admitted from any suitable source of supply, the admission of the steam being controlled by the valves 8. A single closed vessel may be used or a plurality" of these vessels, and when a plurality is used they may be arranged so that the steam from one vessel may be blown into the other, instead of into the atmosphere, so as to utilize the steam in raising the temperature in more than one vessel. As herein shown the closed vessels 1 and 2 are provided with exhausts 9 controlled by Valves 10. Pipes 11 and-12 are connected to pipes 3 and 4 by pipe 13, the various pipes eing controlled by valves 14, 15, 16 and 17. When it is desired to blow oil the steam from vessel 1, for example, into vessel 2, the vessel 1 is rotated about its axis until the exhaust 9 comes into alinement with pipe 11. gether by a suitable coupling 19, and valves 10, 14, 18 and 17 o cried, and valves 15 and 16 closed. It wil thus be seen that the steam will then exhaust into the vessel 2.

When it is desired to exhaust the steam of The two are then connected to- I so as to bring. the exhaust 9 into alinement with the pipe 12, and they are then connected to ether and the valves 10, 15, 18 and 16 opene and the valves 14-and 17 closed. It will be seen that this method results in great economy.

In carrying out the process any suitable form of li no-cellulose may be used, such, for examp e, as comminuted wood of any variety, ,or a mixture thereof, in any sultable form. such as sawdust, chips, shavings, etc., or ligno-cellulose in any form, such as straw,

ligno-cellulose is placed in a closed vessel and is mixed before or after bem placed in the mixture, including that introduced in cellulose and that which may be introduced by or with the steam in the process of heating, should not exceed, after blowing off corn-stalks, or other plant tissues. The

such solution, that contained in the lignothe digester for cooling purposes, twelve times the amount of sugar resulting from the treatment of the ligno-cellulose. One disadvantage of an excessive amount of wateris that the amount of sugar in such water is so .small that an expensive and diflicult process of concentration is necesper cent. or seventeenper cent. The sugar.

of this material, therefore, may be extracted by the diffusion process in the same manner as that used in extracting sugar from beets, and solutions of similar strength obtained therefrom. It will, therefore, be seen that any step to concentrate the solution obtained 7 from this process, before fermentation, is

- under ordinary working conditions.

practice, however, we commonly use from 1 to 5 per centum, but with low temperatures it is possible to use, perhaps, as high as 15 per centum, although always with an.

obviated. The amount of real acid present after such introduction should not exceed six per cent. of such total amount of water In increasing amount of decomposition products for excess of aold naturally increases the cost but it also induces the formation of'certain decomposition products from the ligno-cellulose which hinder the fermentationr The commercial use of the process requires the heatmg of large quantities of material at a time, say, one or more tons, and it has been found that the best .results are secured vby bringingabout the high temperature as quickly as possible.

' The process may be carried on irres ctive of the source from which the hy rolyzing acid is obtained or the manner of applying it to the 'ligno-cellulose, provided such acid is in contact with the ligno-cellulose during the time it is at the temperature 'herein specified. But in any event, the process or treatment should be carried on in such manner and stopped before the advantages of the process are destroyed or rendered unprofitable, as would be the case if there is permitted to be formed in any considerable quantities, pioducts or impurities which are detrimental to fermentation, or which would prevent fermentation of the sugar, and while there is a considerable amount of latitude in carrying out the process, this latter condition must always beborne in mind.

l The material isheated in such, closed vessel preferably by the introduction of live steam in such quantity as to raise the temperature of the entire mass to what is called the crit- I ical point. This is likely to-be in practice a temperature of from two hundred and seventy-five to three hundred and twenty-five degress Fahrenheit. By the term. critical. 5

point. We mean that temperature at which the decomposition products which hllldBI fermentation begin ,to appear in considerable and objectionable quantities, and it ob- 'viously varies somewhat according to the which, for practical purposes, the formation in considerable quantities of such undesirable substances may be saidto have seriously begun. This rise of temperature should be secured as quickly as possible. It is usually securedkin from fifteen to thirty minutes.-

The quicker the rise in temperature the less the tendency to the formation of these undesired decom osition products, or perhaps more proper y termed reversion products,

whether they result from the ligno-cellulose .or the sugar. I In the presence of acids sugar shows a tendency to decomposition at high temperatures, hence the desirability of reaching as quickly as possible the temperature for the maximum hydrolysis whichis coincident with, for the purposes of this process, the so-called critical oint, and also the necessity of quickly re ucing the temperature after the reaction is complete. When this critical point temperature is reached, the material is held at approximatelythattemperature for from ten minutes to an hour, but preferabl under most conditions from thirty to forty-ye minutes. This will depend on various, conditions and among others on the temperature of the critical 'point under the conditions of the particular casein question. By the term reaction we mean, for

practical purposes, the formation of fer- :nentable sugar. The mass of material is then cooled preferably suddenly and this cooling may be brought about by blowin off the gases and vapors from the vesse in which the material is contained. The blowing off is greatly hindered by the presence 'what we call the normal which issubstantially two hundred and twelve degrees Fahrenheit.

AAs previousl suggested, the process can be carried out- 'y operating the series of di-. gesters in succession, so to speak. The first digester in the series is operated in connection with the carrying out of such a process until it has reached the point where the "of a large quantity of water, hence the degases are to be blown ofi. At this time the next digester in the series should have been charged and'brou'ght to the point where it is ready for the reception of the heatin gases. The first digester is now blown 0;,

preferably being blown off into the open air until such impurities which it is desired to eliminate have escaped. It is thenconnected with the second digester so that the latter receives the gases as, for example, the heating steam from the first digester, and in this manner the gases discharged may be passed from digester to digester down the series.

.sulfuric acid. These processes, which may be called the sulfurous acid processes, in-

. volve, therefore, the introduction into the digester of an otherwise unnecessary agent, and the formation within the digester through the action of the agent introduced, of the active or necessary a ent. Wev discovered as the result of actuzil and practical operations along these lines, that this intermediate action could be dispensed with and the required agent, such, for example, as sulfuric or hydrochloric acid, could be introduced directly if proper conditions as to quantity of Water and temperature should be maintained. Another class of investigators had utilized directly the acids in question, but with high temperatures from, say. 325 Fahrenheit up, and large quantities of water or acid carrying solution, say, two and one-half times as much of such solution as of the material to be treated. This process involves, probably on account of the presence of the large volume of water, high temperature, and this leads to an excessive production of reversion and also other products which hinder the process of fermentation.

Moreover, with this large quantity of water the operation, on a commercial scale, becomes slower, and the high temperature must be maintained for a greater length of time, and thus, again, these harmful prod-.

nets are' produced in' excessive quantities. The introduction of such a large quantity of water, necessarily-results in a dilute solution of sugar, and this requires some concentrating process. Efforts have been made to avoid thls by re-usin the sugar solution with a new quantity 0 saw-dust. quantity of water is not greatly reduced the process of distilling is seriously interfered with. We discover that these strongly hydrolyzing acids could be successfully used in If the i that is an amount of water less than two and one-half times the amount of saw-dust, if operated with a relatively low temperature, that-is, a temperature, say, less than 325 Fahrenheit as explained heretofore in -our discussion of the term critical point.

In this event, the temperature can be raised quickly because of the absence of Water and it may be raised in from 15 minutes to an hour, the usual practice being about 15 minutes. Thus by our process, as compared with the prior practice to which we have referred, we obviate, on the one hand, the introduction of the indirectagent and the formation of the direct agent within the digester, and, on the other hand, we obviate the difi'iculties due to the necessity of concentration incident to the presence of large quantities of water, and the formation of products interfering with fermentation incident to high temperatures.

As an example of one way inwhich our invention may be realized, we shall briefly state an actual experience. We took about 4,000 lbs. of saw-dust containing 30% of moisture and introduced this into the digester. At the same time and, along with it, and so as to mix the acid with the saw-dust, we introduced about 50 lbs.'of degree sulfuric acid previouslydiluted with about 200 parts of water". The tank was then closed and steam.

at about 100 lbs. pressure was turned into the tank. The digester was set in motion and the supply of steam continued for about fifteen minutes or until the temperature reached about -310 degrees. The steam was then cut ofl, but the rotation of the digester continued for about thirty minutes. We then blew ofl' the gases and vapors and took out the. material, when it appeared like moist saw-dust and was ready for further treatment to recover'the sugar.

We claim:

1. The process of producing fermentable sugars from ligno-cellulose which consists in placing a quantity of it in a closed vessel with not to exceed two and one-half times its weight of water, supplying to the vessel the described quantity of a strongly hydrolyzing acid such as sulfuric acid or hydrochloric ac'id, quickly raising the temperature connection with a small amount of water, of the mixture to about the described critical point, by applying steam thereto, maintaining such temperature until the re-action is completed and then quickly reducing the temperature to at least the boiling point of Water.

3. The process of producing fermentable sugars from ligno-cellulose which consists in placing a quantity of it. in a closed vessel with not to exceed two and one-halftimes its weight of water, supplying to the vessel the describedquantity of a strongly hydrolyzing' acid such as sulfuric acid or hydrochloric acid, quickly raising the temperature of the mixture to about the described crit ical point, maintaining such temperature for from thirty to forty-five minutes or until the re-action is completed, and then quickly reducing the temperature to at least the boiling point of water. L v

4. The process of producing fermentable sugars from ligno-cellulose which consists in placing a quantity of it in a closed vessel, with not to exceed two and one-half times its weight of water, supplying to the vessel the described quantity of a strongly hydro-' lyzin acid such as sulfuric acid or hydrochloric acid, quickly raisin the temperature of the mixture to about t e described critical point by applying steam thereto, mains tainin such temperature for from thirty to fortyve minutes or until the re-actionis completed and then quickly reducin the temperature to at least the boiling point of water. a

5. The process of producing fermentable sugars from ligno-cellulose which consists in placing a quantity of it in a closed vessel withnot to exceed'two and one-half times its weight of water, supplying to'the vessel the described quantity of a strongly hydrolyzing acid such as sulfuric or hydrochloric acid, quickly raising the temperature of the mixture to about the described critical point, and maintaining such tem erature untilthe re-action is completed, an then quickly reducing the temperatureto at least the boiling point of water by blowing oil. the gases and vapors in the vessel.

6. The process of producing fermentable sugars from ligno cellulose which consists in placing a quantity of it in a closed vessel,

with not toexceed two and one-half times chloric acid, quickly raising the temperature of the mixture to about'the described critical point by applying steam thereto, maintaining such temperature until the re-action is completed and then quickly reducing the temperature to at least the boiling .point of water by blowing off the gases and vapors in the vessel.

7. The process of producing its weight of water, supplying to the vessel the described quantity of a strongly hydro- 4 lyzin i chlor1c acid, quickly raising the temperature acid such as sulfuric acid or hydroof the mixture to about the described critical fermentable sugars from ligno-cellulose WhlCh consists in :placing a quantity of it in a closed vessel with not to exceed two and one-half times point,maintaining such temperature for from a thirty to forty-five minutes or until thereaction is completed, and then quickly reduc ing'the temperature to at least the boiling point of water by blowing off the gases and vapors in the vessel.

'8. The process of producing fermentable sugars from ligno-cellulose whichco'nsists 1n placing a quantity of it in a closed vessel,

with not to exceed two and one-half times its weight of water, supplying to the vessel the described quantity of a stronglyhydrolyzing acid such as sulfuric acid or hydrochloric acid, quickly raising the temperature of the mixture to about the described crit-' ical point by applying steam thereto, maintainin such temperature for from thirty to fortyve minutes, or until the re-action is completed and then quickly reducing the temperature to at least the boiling point of water by blowing off the gases and vapors in the vessel.

MALCOLM F. EWEN.

GEORGE H. TOMLINSON. 

